1. Field of the Invention
The present invention relates to a cooking heater that heats an object to be cooked which is placed inside a heat chamber through an opened door.
2. Description of the Related Art
Conventionally, many cooking heaters with a front opening/closing door such as microwave oven have been proposed, and a forward pullout type cooking heater has also been proposed as a different type of cooker. Since the pullout type cooking heater is suitable in a relatively large structure, it is appreciated as one of cookers composing an integrated kitchen system. Reflecting upsizing and systematization of a kitchen in recent years, cookers are also being more and more diversified and unitized and a cook-top, pullout type cooker in which a microwave oven and electric oven are combined in a single unit has been proposed.
As an example of pullout type cooking heater, there has been proposed a cooking heater structured in such a way that a bottom plate which moves in synchronization with a front opening/closing door is “smoothly” slidable with respect to the apparatus body by means of a slide mechanism and the bottom plate is driven to open/close together with the opening/closing door by transmitting the output of a motor provided on the apparatus body through transmission means such as a pinion rack mechanism (see Japanese Patent Laid-Open Publication No. 3-45820 (line 5 at top left to line 16 at top right on page 3, FIG. 2 to FIG. 4)). The door opening/closing device is provided with a latch device which keeps the opening/closing door closed, a door opening/closing switch and a control circuit which receives a signal from this door opening/closing switch and drives a motor to open/close the opening/closing door, and pressing the door opening/closing switch automatically releases the latch and a driving force of the motor causes the opening/closing door to open/close in synchronization with the bottom plate.
As another example of the pullout type cooking heater, there has been proposed a cooking heater provided with a drawing member in which an object to be heated is housed in a drawable manner inside the cooker body, wherein when it is detected that the drawing member is drawn forward, electromagnet legs provided on the bottom face of the cooker body are excited so as to be attracted to a metal mount surface on which the cooker is placed (see Japanese Patent Laid-Open Publication No. 6-109257 (paragraph [0010], FIG. 1)). When the drawing member in which a large-volume object to be heated is placed is pulled out, the electromagnet legs are attracted to the metal mount surface, and therefore it has been intended to prevent the drawing member from losing its weight balance and toppling over forward from a kitchen counter.
As another example of the pullout type cooking heater, there has been proposed a microwave oven having a drawable structure with a movable food mount (see Japanese Patent Laid-Open Publication No. 11-237053 (paragraphs [0030] to [0035], FIG. 1)). This microwave oven provides a cooking container having an opening at the top such that it is freely drawable from the housing of the body of the microwave oven, the cooking container and a cover which covers the opening of the cooking container provided on the body housing side form a heat chamber which can trap micro wave. This microwave oven provides a choke groove between the perimeter of the opening of the cooking container and a cover facing this to prevent leakage of radio wave.
The applicant of the present invention proposes a cooking heater provided with a drawing member in which an object to be heated is accommodated in a manner drawable from the cooker body (Japanese Patent Application No. 2004-7384, Japanese Patent Application No. 2004-7385). According to the proposal of the former application, it is possible to eliminate the necessity for using expensive parts or materials having high thermal resistance and flame resistance to construct a movable mechanism, thereby reduce manufacturing costs and adopt a moving mechanism without being affected by micro wave irradiated into the heat chamber to thereby eliminate the possibility of discharge caused by micro wave. On the other hand, according to the latter application, it is possible to prevent a sudden boiling phenomenon that an overheated liquid is vaporized by a shock such as vibration when vibration caused by the opening/closing operation is applied to the object to be heated and the vapor is discharged at a stroke, causing the user to get burned and it is possible to control the moving speed of the opening/closing door so as to prevent the object to be heated from toppling over or liquid component from spilling due to the shock of the opening/closing operation. Furthermore, by constructing the moving mechanism without using expensive parts or materials having high thermal resistance and flame resistance, it is possible to reduce the manufacturing cost and cause the moving mechanism to have a structure unaffected by micro wave irradiated into the heat chamber and thereby eliminate the possibility of discharge caused by micro wave.
In the case of a composite cooking apparatus combining a cook-top section, microwave oven section and electric oven section in a single unit, if the door of the electric oven is closed with a bang when the microwave oven section is in use, reaction against the collision between the door of the electric oven and front plate causes a force to act on the door of the microwave oven section built in adjacent to the electric oven section in the door opening direction. The shock at this time may not cause the door of the microwave oven section to open, but may cause the latch head in the latch mechanism section to float momentarily. At that time, the latch switch turns OFF momentarily and a signal indicating that the door is opened is inputted to a control section of the microwave oven section. As for control of the microwave oven section, when, for example, an OFF-state of the latch switch of the door continues for 50 ms, for example, the door is judged to be opened, the operation of the microwave oven section is stopped and that information is displayed or alarmed by an operation display of the cooker or alarm sound or the like. When the operation of the microwave oven section stops and the user who becomes aware of the display or alarm responds to such stoppage of operation, cooking with the microwave oven section may be suspended for a long time, which makes continuation of cooking and post-treatment more complicated or may also result in an insufficient cooling condition. In the case of not only a composite cooker but also a cooking heater with a stand-alone pivoted door type microwave oven, when a person or an object may collide with the microwave oven directly or with the mount on which the microwave oven is placed and the microwave oven is strongly shaken, the operation of the microwave oven may be suspended for the similar cause of momentary opening of the door switch.
Even when the door switch is turned OFF momentarily due to a momentary shock acting on the door of the cooking heater, this may not lead to a situation in which the total operation of the cooking heater should be stopped. Therefore, based on such a judgment, there is a problem to be solved in trying to continue the operation of the cooking heater within a certain limit while securing safety.
It is an object of the present invention to provide a cooking heater capable of, when a force in the door opening direction is applied caused by a shock applied to the cooking heater during operation of the cooking heater, which may not cause the door to actually open but may momentarily turn OFF the door switch, apparently continuing the operation of the cooking heater without stopping it if the OFF-state is within a predetermined limit thus avoiding inconvenience of forcing the user to take complicated actions.